WNCG research

Resolution-Adaptive Hybrid MIMO Architectures for mmWave Communication

Moving to a millimeter wave (mmWave) spectrum in range of 30-300 GHz enables the utilization of multi-gigahertz bandwidth and offers an order of magnitude increase in achievable rate. The small wavelength allows a large number of antennas to be packed into transceivers with very small antenna spacing. Leveraging the large antenna arrays, mmWave systems can manipulate directional beamforming to produce high beamforming gain, which helps overcome large free-space pathloss of mmWave signals.

WNCG Introduces New Affiliate Membership Level

Effective February 2015, WNCG is pleased to announce the introduction of a new Level III membership option in its Industrial Affiliate Program. The Industrial Affiliate Program allows companies to become stakeholders in WNCG and to participate in the growth and direction of the center. Initially founded to significantly lower the cost of pre-competitive research for each sponsor, the program maximizes benefits to each sponsoring company.

Student Tianyang Bai awarded Qualcomm Roberto Padovani Fellowship

In recognition of his outstanding performance as a summer intern, Qualcomm awarded WNCG Ph.D. student Tianyang Bai the Roberto Padovani Fellowship. 

The fellowship was created in 2008 to recognize Qualcomm’s corporate research and development interns who demonstrate superior technical performance during their summer internship. Roberto Padovani was Qualcomm’s chief technology officer for nearly 10 years and was a leading innovator for the company.

WNCG Alum Karl Nieman and NI Create First 100-Antenna Massive MIMO Base Station Model

Modern communication systems rely on multiple antennas that enhance the performance of network links using a series of techniques known as Multiple Input Multiple Output (MIMO). However, new technology is needed to meet the demands of a rapidly increasing number of wireless devices and enable the next generation of cellular systems. Known as Massive MIMO, this adaptation of traditional MIMO techniques presents challenges to research and development teams worldwide. 

Analysis of Self-Body Blocking Effect in mmWave Cellular Networks

The millimeter wave (mmWave) spectrum is a strong candidate carrier frequency for access channels in 5G cellular networks. Unfortunately, measurements show the human body heavily attenuates mmWave signals, e.g. by a factor of 20-40 dB. Consequently, users’ bodies may attenuate the direct signal, cause signal outage, and further change the base station associations. The effect of self-body blocking was not incorporated in prior performance analysis of mmWave cellular networks.

Channel Estimation in Millimeter Wave MIMO Systems with One-Bit Quantization

Millimeter wave (mmWave) is a technology that can provide high bandwidth communication links in cellular systems. As mmWave uses larger bandwidths, the corresponding sampling rate of the analog-to-digital converter (ADC) scales up. Unfortunately, high speed, high resolution (e.g., 6-12 bits) ADCs are costly and power-hungry for portable devices. A possible solution is to live with ultra low resolution ADCs (1-3 bits), which reduces power consumption and cost.

Performance Analysis of Pair-Wise Dynamic Multi-User Joint Transmission

In multi-cell cooperative networks, base station (BS) cooperation with BS clustering is indispensable for alleviating cooperation costs (e.g., data and channel estimation sharing via backhaul links). The performance of such BS cooperation is fundamentally limited by the unmanageable out-of-cluster interference. The out-of-cluster interference power is mainly a function of a set of the distances from the out-of-cluster BSs to users, the path-loss exponent, the cluster size, and the cooperative transmission strategies used in the out-of-cluster.

Cooperative Base Station Coloring for Pair-Wise Cluster Multiplexing

Coordination among base stations (BS) is a powerful approach for mitigating inter-cell interference and maximizing the sum spectral efficiency in cellular systems. In practice, however, coordination with a large number of BS may not be feasible due to excessive overheads associated with BS coordination, e.g., complexity, channel estimation and channel feedback. One practical solution for implementing multi-cell coordination is, therefore, to form a BS cluster so that a limited number of BS are coordinated to control intra-cluster interference with a reasonable amount of overhead.

Performance Analysis of Millimeter Wave Ad Hoc Networks

Ad hoc networks provide a flexible, infrastructure-free means to communicate between soldiers in war zones, aid workers in disaster areas, or consumers in device-to-device (D2D) applications. Ad hoc networks, however, are still plagued by interference caused by uncoordinated transmissions which leads to poor scaling due to distributed coordination. Communication with millimeter-wave (mmWave) devices offers hope to 
ad hoc networks through higher bandwidth, reduced interference due to directional antennas, and weaker interference power due to building blockage. 

Understanding Ultra-Dense Cellular Networks: Multi-slope Path Loss Models and Analysis

Existing cellular network analyses, and even simulations, typically use the standard path loss model where received power decays 1/d^x over a distance d, with a pathloss exponent x. This model leads to tractable analysis of downlink cellular network performance with base stations distributed by a Poisson point process. However, it is widely known that this standard path loss model is quite idealized, and that in most scenarios the path loss exponent x is itself a function of d.


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